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Toxicity to terrestrial arthropods

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Endpoint:
toxicity to terrestrial arthropods: short-term
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Reason / purpose for cross-reference:
reference to same study
Qualifier:
equivalent or similar to guideline
Guideline:
ISO 11267 (Inhibition of Reproduction of Collembola by Soil Pollutants)
Principles of method if other than guideline:
Folsomia fimetaria and Hypogastrura assimilis (springtail): The aim of study was to study the effects of sodium salt of linear alkyl benzene sulphonates (C10-13 LAS) on reproduction of the two springtail species. Test species (ten male and ten female) were exposed to the test substance through soil after 24 hours equilibration of the test soil. The containers were incubated for 21 day. After incubation, the animals were extracted using MacFadyen high-gradient extraction and the number of offspring were counted.

Predacious mite test: No internationally accepted guideline is available for mite reproduction. Effects on reproduction on the predacious mite (Hypoaspis aculeifer Canestrini) were examined according to a method described by Krogh and Axelsen (1998). Ten female and five male H. aculeifer (16-19 days old) were added to each test container together with 100 F. fimetaria (16-19 days old) serving as prey for the mites. Water content of test soil was surveyed by control weighing of containers after 14 d and adjusted if necessary. Incubation and extraction of mite offspring followed the same procedure as described for springtails.
GLP compliance:
not specified
Application method:
not specified
Analytical monitoring:
not specified
Details on sampling:
- Sample storage conditions before analysis: The soil samples were stored in glowed glass jars at -20°C until analysis.
Vehicle:
not specified
Details on preparation and application of test substrate:
Method of mixing into soil (if used):
Springtail: Twenty-seven grams dry weight of soil were mixed with 3 mL of LAS solution and filled into cylindrical test containers with lids. The bottom of the cylinder consisting of a 1-mm mesh to allow later extraction of the test animals. The mesh was covered with a layer of plastic film to prevent escape of the test animals.
Mite: A total of 54 g dry weight of soil was mixed with 6 mL of LAS solution and filled into test containers (as described for springtails).
Test organisms (species):
other: Folsomia fimetaria, Hypogastrura assimilis, Hypoaspis aculeifer
Animal group:
other: soil-dwelling
Details on test organisms:
- Common name: Springtail (Folsomia fimetaria and Hypogastrura assimilis) and predacious mite (Hypoaspis aculeifer)
- Age at test initiation: F. fimetaria (23-26 days old), and H. aculeifer (16-19 days old), and H. assimilis (16-19 days old)
Study type:
laboratory study
Limit test:
no
Total exposure duration:
21 d
Details on test conditions:
TEST SYSTEM
- Test container (material, size): cylindric test containers (height, 5.5 cm; diameter, 6 cm) with lids.
- Amount of soil or substrate: 27 g of dry soil for Springtail tests and 54 g of dry soil for predacious mite
- No. of organisms per container (treatment): Ten male and 10 female F. fimetaria and Hypogastrura assimilis; Ten female and 5 male H. aculeifer
- No. of replicates per vehicle control: No vehicle control used

SOURCE AND PROPERTIES OF SUBSTRATE (if soil)
- Geographic location: Natural sandy, agricultural soil was collected from Askov experimental station, Danish Institute of Agricultural Sciences, Denmark
- Soil texture (if natural soil)
- % sand (fine and coarse): 82.7
- % silt: 8.6
- % clay: 6.2
- % humus: 2.7
- pH: 5.5
- Soil taxonomic classification: Sandy soil
- Cation-exchange capacity: 3.2 mEq/100 g
- Pretreatment and storage of soil: The soil was dried at 80°C, sifted through a 2-mm mesh, and stored at room temperature until use.

OTHER TEST CONDITIONS (only for springtails species)
- Photoperiod: 12 hours dark and 12 hours light


EFFECT PARAMETERS MEASURED (with observation intervals if applicable): The number of offspring were counted for all the three species

VEHICLE CONTROL PERFORMED: no
Nominal and measured concentrations:
Springtail: The test concentrations were not listed but can be estimated from Figure 6 to be 0, 10, 25, 75, 275, and 800, with the numbers of adult surviving per replicate to be approximately 145, 155, 115, 110, 165, and 165 and the numbers of juveniles per replicate (reproduction) to be approximately 285, 275, 190, 145, 205, and 10.
Reference substance (positive control):
not specified
Key result
Duration:
21 d
Dose descriptor:
EC10
Effect conc.:
82 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
reproduction
Remarks on result:
other: Hypoaspis aculeifer (95% CL: 14- 167 mg/kg soil dw)
Key result
Duration:
21 d
Dose descriptor:
EC10
Effect conc.:
99 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
reproduction
Remarks on result:
other: Hypogastrura assimilis (95% CL: 0-164 mg/kg soil dw)
Key result
Duration:
21 d
Dose descriptor:
EC10
Effect conc.:
85 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
reproduction
Remarks on result:
other: Folsomia fimetaria (95% CL: 18- 152 mg/kg soil dw)
Key result
Duration:
21 d
Dose descriptor:
LC10
Effect conc.:
> 793 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mortality
Remarks on result:
other: Folsomia fimetaria and Hypoaspis aculeifer
Details on results:
Springtail tests: Reproduction in the springtail F. fimetaria was reduced by 50% at approximately 420 mg/kg, whereas survival was unaffected, even at the highest concentration of 793 mg/kg. Reproduction in the other springtail (Hypogastrura assimilis) was reduced by 50% at approximately 421 mg/kg. Effects on survival were not assessed in this species, however, because the earliest produced juveniles rapidly matured and were not discernible from the added adults.

Predacious mite test: Survival of adult mites (Hypoaspis aculeifer) was not affected, even at the highest concentration of 793 mg/kg, whereas reproduction was reduced by 50% at a concentration of approximately 236 mg/kg.

It should be noted that these studies report worst case exposures due to the use of a sandy test soil and the fact that LAS was added as an aqueous solution to the soil. In addition, too few replicates were used for the ECx approach (e.g., <5 controls) and several key deviations from draft protocols limited the reliability of endpoints for some studies (e.g., A. caliginosa and A. longa cocoon production). Nominal concentrations were derived from tables and figures since actual values were not found in the text.

The following table shows the results of all tests.  All values are nominal LAS concentrations in mg/kg dry weight.

Species

Parameter

NOEC

LOEC

LC10 or EC10

LC50 or EC50

Reliability Rating

Rationale for Reliability Rating

Enchytraeus albidus

Survival, adults

Reproduction

198

20

397

40

194

6

430

41

1

1

Draft ISO/WD 16387 protocol

Aporrectodea caliginosa

Survival, adults

Cocoon production

Survival, juveniles

Growth, juveniles

278

>793

>397

278

793

>793

>397

397

329

14

>397

105

535

129

>397

354

2

3

2

2

Comparable to

ISO 11268-2

Deviations; limited cocoons

Comparable to ISO 11268-2, but with only weight measurement

Aporrectodea longa

Survival, adults

Cocoon production

Survival, juveniles

Growth, juveniles

278

>793

397

79

793

>793

793

278

329

27

296

84

535

137

517

349

2

3

2

2

Comparable to

 ISO 11268-2

Deviations; limited cocoons

Comparable to ISO 11268-2, but with only weight measurement

Folsomia fimetaria

Survival, adults

Reproduction

>793

278

>793

278

>793

85

>793

424

1

1

Comparable to  ISO 11267

Hypogastrura assimilis

Reproduction

79

278

99

421

1

Comparable to  ISO 11267

Hypoaspis aculeifer

Survival, adults

Reproduction

>793

278

>793

793

>793

82

>793

236

2

2

No guideline available

Validity criteria fulfilled:
yes
Conclusions:
In three reproduction tests of sodium salt of linear alkyl benzene sulphonates (C10-C13) with soil invertebrates, the EC10 values were 85, 99 and 82 mg/kg dry weight for Folsomia fimetaria, Hypogastrura assimilis and Hypoaspis aculeifer, respectively.

Survival of Folsomia fimetaria and Hypoaspis aculeifer was not affected, even at the highest concentration of 793 mg/kg. Effects on survival of Hypogastrura assimilis were not assessed in this species, however, because the earliest produced juveniles rapidly matured and were not discernible from the added adults.
Executive summary:

The aim of study was to study the effects of sodium saltoflinear alkyl benzene sulphonates (C10-13 LAS) on reproduction of the springtails and predacious mite.

Ten male and ten female of two springtails species(Folsomia fimetaria and Hypogastrura assimilis) were exposed to the test substance through soil after 24 hours equilibration of the test soil. In another test, ten female and five male Hypoaspis aculeifer were added to each test container together with 100 Folsomia fimetaria serving as prey for the mites. The containers were incubated for 21 day. After incubation, the animals were extracted using MacFadyen high-gradient extraction and the number of offspring were counted.

Reproduction in the Folsomia fimetaria, Hypogastrura assimilis and Hypoaspis aculeifer was reduced by 50% at approximately 424, 421 and 236 mg/kg, respectively. Survival of Folsomia fimetaria and Hypoaspis aculeifer was not affected, even at the highest concentration of 793 mg/kg, whereas the effects on survival for Hypogastrura assimilis were not assessed because the earliest produced juveniles rapidly matured and were not discernible from the added adults.

In three reproduction tests of sodium salt of linear alkyl benzene sulphonates (C10-C13) with soil invertebrates, the EC10 values were 85, 99 and 82 mg/kg dry weight for Folsomia fimetaria, Hypogastrura assimilis and Hypoaspis aculeifer, respectively. Survival of Folsomia fimetaria and Hypoaspis aculeifer was not affected, even at the highest concentration of 793 mg/kg.

Endpoint:
toxicity to terrestrial arthropods: long-term
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Reason / purpose for cross-reference:
reference to same study
Qualifier:
no guideline followed
Principles of method if other than guideline:
The toxicity of Na LAS to the reproductive output of soil dwelling organisms (Folsomia fimetaria) was tested in three soil types (Sandy soil, loamy soil and clayey soil). In other set of tests, various LAS salts (Na, Ca, and Mg) were tested in one soil type (sandy) to determine the effect of speciation to toxicity. Another experiment was conducted to determine the influence of sewage sludge on toxicity in which sewage sludge spiked Na-LAS was mixed with sandy soil. In each test, 10 male and 10 female organisms were placed in containers with test substance added to the soil. Exposure lasted 21 days, at the end of which the number of adult and juvenile organisms were counted.
GLP compliance:
no
Application method:
soil
Analytical monitoring:
yes
Details on sampling:
Soil samples: 30 g soil samples were stored in glowed glass jars at -20 degrees C until analysis.
Sewage sludge samples: Sludge suspensions were stored in air-tight, glass containers at 1°C.
Vehicle:
yes
Details on preparation and application of test substrate:
Soil spiked tests: Appropriate LAS solutions were prepared by dilution of stock solutions (Na-LAS: demineralized water; Ca-LAS and Mg-LAS: acetone) and thoroughly mixed with the test soil to give LAS anion concentrations as great as 960 mg/kg dry soil.

Acetone was used in the Ca-LAS and Mg-LAS tests as these compounds are insoluble in water.

Sewage sludge spiked tests: Sludge suspensions were made by mixing 68.3 g of raw sludge (dry matter content, 23%) plus 31.7 g of water with 50 g of Na-LAS–water solutions of various concentrations, resulting in LAS–sludge suspensions with water contents of approximately 89.5% (w/w) water. These suspensions were made 1, 7, or 14 day before mixing with the test soil, and until then, they were stored in air-tight, glass containers at 15°C. The day before the experiment, the LAS–sludge suspensions were diluted with appropriate volumes of water and thoroughly mixed with the test soil (sandy soil), resulting in soil moisture contents equal to those described in the previous section.
Test organisms (species):
Folsomia sp.
Animal group:
Collembola (soil-dwelling springtail)
Details on test organisms:
TEST ORGANISM
- Age at test initiation (mean and range, SD): 23-26 days

Study type:
laboratory study
Total exposure duration:
21 d
Test temperature:
20 degrees C
pH (if soil or dung study):
5.5-5.8
Photoperiod and lighting:
12:12 photoperiod
Details on test conditions:
TEST SYSTEM
- Test container (material, size): 5.5 x 6 cm cylindrical containers
- Amount of soil or substrate: 30 g moist soil
- No. of organisms per container (treatment): 10 male/10 female
- Food: Dried baker’s yeast

SOURCE AND PROPERTIES OF SUBSTRATE (if soil)
- Geographic location: Lundgaard, Danish Institute of Agricultural Sciences
- Soil texture (if natural soil)
- % sand: 66.9 coarse, 15.8 fine
- % silt: 3.3 coarse and 5.3 fine
- % clay: 6.2
- Soil classification system: sandy soil
- Total carbon (%): 1.5
- Individual CEC: 2.89 (Ca+2), 0.16 (K+), 0.12 (Mg+2) and 0.06 (Na+) mEq/100 g
-Total CEC: 3.23 mEq/100 g
- iron oxy-hydroxides (dithionite) (ppm): 3800
- aluminium oxy-hydroxides (dithionite) (ppm): 1410
- Humus (%): 2.7
- pH: 5.5
- Pretreatment of soil: The soil samples were dried at 80 degrees C, sifted through 2 mm mesh and stored at room temperature until use

SOURCE AND PROPERTIES OF SUBSTRATE (if soil)
- Geographic location: Askov, Danish Institute of Agricultural Sciences
- Soil texture (if natural soil)
- % sand: 38.4 coarse, 23.6 fine
- % silt: 10.0 coarse, 12.3 fine
- % clay: 13.0
- Soil classification system: loamy soil
- Total carbon (%): 1.6
- Individual CEC: 7.54 (Ca+2), 0.23 (K+), 0.26 (Mg+2) and 0.12 (Na+) mEq/100 g
-Total CEC: 8.14 mEq/100 g
- iron oxy-hydroxides (dithionite) (ppm): 4600
- aluminium oxy-hydroxides (dithionite) (ppm): 1340
- Humus (%): 2.8
- pH: 6.2
- Pretreatment of soil: The soil samples were dried at 80 degrees C, and sifted through 2 mm mesh and stored at room temperature until use

SOURCE AND PROPERTIES OF SUBSTRATE (if soil)
- Geographic location: Flakkebjerg, Danish Institute of Agricultural Sciences
- Soil texture (if natural soil)
- % sand: 23.4 coarse, 25.5 fine
- % silt: 18.8 coarse, 15.4 fine
- % clay: 15.1
- Soil classification system: clay soil
- Total carbon (%): 1.0
- Individual CEC: 9.66 (Ca+2), 0.24 (K+), 0.21 (Mg+2) and 0.06 (Na+) mEq/100 g
-Total CEC: 10.16 mEq/100 g
- iron oxy-hydroxides (dithionite) (ppm): 4600
- aluminium oxy-hydroxides (dithionite) (ppm): 570
- Humus (%): 1.8
- pH: 7.2
- Pretreatment of soil: The soil samples were dried at 80 degrees C, and sifted through 2 mm mesh and stored at room temperature until use.

SOURCE AND PROPERTIES OF SUBSTRATE (SEWAGE SLUDGE)
- Source: The sewage sludge used in the experiments was obtained from a Danish wastewater treatment plant (Community of Skaevinge, Skaevinge, Denmark) receiving wastewater predominantly from nonindustrial sources.

OTHER TEST CONDITIONS
- Photoperiod: 12:12

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : The number of surviving adults and juveniles were counted on day 21.
Nominal and measured concentrations:
Nominal concentrations for Na LAS in the springtail reproduction test using different salts of LAS: 0, 99, 198, 397, 595 and 793 mg/kg dry wt

Nominal concentrations for Na LAS in the springtail reproduction test using different soil types: 0, 8, 28, 79, 278, 793 mg/kg dry weight

The measured concentrations for both these tests are provided in Table 1 and 2 of “Any other information on materials and methods incl. tables” section.
Reference substance (positive control):
no
Key result
Duration:
21 d
Dose descriptor:
EC10
Effect conc.:
85 mg/kg soil dw
Nominal / measured:
meas. (not specified)
Basis for effect:
reproduction
Remarks on result:
other: 95% CI: 18-52 mg/kg soil dw
Remarks:
(Na-LAS in sandy soil)
Key result
Duration:
21 d
Dose descriptor:
EC10
Effect conc.:
93 mg/kg soil dw
Nominal / measured:
meas. (not specified)
Basis for effect:
reproduction
Remarks on result:
other: 95% CI:0-126 mg/kg soil dw
Remarks:
(Na-LAS in clay soil)
Key result
Duration:
21 d
Dose descriptor:
EC10
Effect conc.:
87 mg/kg soil dw
Nominal / measured:
meas. (not specified)
Basis for effect:
reproduction
Remarks on result:
other: 95% CI: 51-123 mg/kg soil dw
Remarks:
(Na-LAS in sandy soil)
Key result
Duration:
21 d
Dose descriptor:
EC10
Effect conc.:
106 mg/kg soil dw
Nominal / measured:
meas. (not specified)
Basis for effect:
reproduction
Remarks on result:
other: 95% CI: 71-140 mg/kg soil dw
Remarks:
(Ca-LAS in sandy soil)
Key result
Duration:
21 d
Dose descriptor:
EC10
Effect conc.:
97 mg/kg soil dw
Nominal / measured:
meas. (not specified)
Basis for effect:
reproduction
Remarks on result:
other: 95% CI: 71-124 mg/kg soil dw
Remarks:
(Mg-LAS in sandy soil)
Details on results:
INFLUENCE OF SALT SPECIATION OF LAS - Survival and reproductive output for all the LAS salts was almost same. There was no significant effect of speciation on the toxicity.
- For Na-LAS, the control reproduction was lower than reproduction at test concentrations of 99 and 198 mg/kg.

INFLUENCE OF SOIL TYPE
- There seemed to be no effect of LAS at less than 793 mg/kg on survival using the sandy soil as test medium.
- In sandy loam, adult survival was reduced by 75% at 793 mg/kg, but this reduction was not statistically significant.
- In clayey soil, adult survival was significantly reduced at 278 mg/kg or greater.
- Reproductive output was significantly reduced at 793 mg/kg in sand and sandy loam and at 278 mg/kg in clayey soil. The EC50s of reproductive output were found in the range of 34 to 424 mg/kg for the three soils tested, but no statistically significant differences were found between the soils.

INFLUENCE OF SEWAGE SLUDGE ON TOXICITY
The type of sludge used in these experiments apparently did not have any negative influence on reproductive performance.
- Adult survival was not significantly reduced at the highest concentration (NOEC: 512 mg/kg) when sludge had been spiked 1 day before the experiment.
- However, anaerobic incubation for 7 and 14 day of the LAS–sludge suspension (with no decay of LAS) caused the toxicity to increase almost threefold, with estimated LOECs being 256 and 128 mg/kg for 7 and 14 days, respectively.
This same pattern was seen for reproductive output, in which the LOEC decreased from 256 for 1 day- and 7-day incubation to 128 mg/kg for 14-day incubation of LAS-sludge slurries.
Reported statistics and error estimates:
NOEC and LOEC were determined by comparing the control with each concentration tested using a Dunnett’s test in an analysis of variance procedure. The validity of the analysis of variance was tested using SASt/LAB software, checking for homogeneity of variances (i.e., Levene’s test), outliers, and normality of data. When necessary, data were transformed according to the transformation suggested by the SAS/LAB program. Estimation of the LC10 and LC50 was done using probit analysis. Estimation of the EC10 and EC50 was done, when possible, by fitting data to a regression model using PROC NLIN and, when not, by using the inhibition concentration approach.
Validity criteria fulfilled:
not specified
Remarks:
(No guideline was followed)
Conclusions:
The EC10 for Folsomia fimetaria in various soils ranged from 85-93 mg/kg dry weight soil.
Executive summary:

Groups of 10 male and 10 female Folsomia fimetaria were exposed to various concentrations of Na-LAS in three different soil types for 21 days. At the end of this period, the number of adult and juvenile organisms was counted. Another test was done to compare the toxicity of three LAS salts, Na, Ca, and Mg, in one soil type (sandy). There was little variation in toxicity among the three soil types and in the three salt species. The EC10 for Folsomia fimetaria in various soils ranged from 85-93 mg/kg dry weight soil.

Endpoint:
toxicity to terrestrial arthropods: long-term
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Reason / purpose for cross-reference:
reference to same study
Qualifier:
according to guideline
Guideline:
ISO 11267 (Inhibition of Reproduction of Collembola by Soil Pollutants)
GLP compliance:
no
Application method:
soil
Analytical monitoring:
yes
Details on sampling:
Initial concentrations were measured.
Vehicle:
yes
Details on preparation and application of test substrate:
LAS was mixed in demineralized water, and then added to dry Askov soil. Fresh sludge (approx. 200 g) was freeze-dried. This was crushed and sieved through a 2 mm sieve. A methanol solution of LAS was then added to the sludge.
Test organisms (species):
Folsomia candida
Animal group:
Collembola (soil-dwelling springtail)
Details on test organisms:
TEST ORGANISM
- Source: permanent laboratory cultures
- Age at test initiation (mean and range, SD): 10-12 days

Study type:
laboratory study
Limit test:
no
Total exposure duration:
28 d
Details on test conditions:
TEST SYSTEM
- Amount of soil or substrate: 26 g soil mixed with 4 ml test solution
- No. of replicates per treatment group: 3

SOURCE AND PROPERTIES OF SUBSTRATE (if soil)
SOIL
- Geographic location: The soil was a Danish sandy loam collected from Askov, Jutland.
- Soil texture (if natural soil)
- % sand (Fine and coarse): 76
- % silt: 12
- % clay: 11
- Soil classification system: sandy loam
- Organic carbon (%):1.3
- Humus (%): 2.5
- pH: 6.18
- Potassium (meq/100 g): 0.50
- Sodium (meq/100 g): 0.09
- Magnesium (meq/100 g): 0.48
- Calcium (meq/100 g): 5.6
- CEC: 13.4
- Pretreatment of soil: The soil was defaunated by heating to 80°C for 24 h in an oven.

EFFECT PARAMETERS MEASURED (with observation intervals if applicable): After
28 days of incubation with the test soil, the animals were extracted from the soil using a high gradient heat extractor and counted.

Nominal and measured concentrations:
LAS directly spiked to soil test: 0 and 25-300 mg a.i./kg soil

LAS spiked to sludge test: 0 and 300 mg a.i./kg soil, corresponding to 0 and 181 g a.i./kg freeze-dried sludge
Reference substance (positive control):
no
Key result
Duration:
28 d
Dose descriptor:
EC10
Effect conc.:
205 mg/kg soil dw
Nominal / measured:
nominal
Basis for effect:
reproduction
Remarks on result:
other: 95% CL: 8.6–401 mg/kg soil dw
Key result
Duration:
28 d
Dose descriptor:
LC10
Effect conc.:
261 mg/kg soil dw
Nominal / measured:
nominal
Basis for effect:
mortality
Remarks on result:
other: 95% CL: 114–408 mg/kg soil dw (adults)
Details on results:
LAS DIRECTLY SPIKED TO SOIL TEST:
- Survival of adult Folsomia candida was affected only slightly by LAS at the highest test concentration, with an LC10 of 261 mg a.i./ kg soil.
- Reproduction was not significantly affected, but an indicative EC10 was estimated at 205 mg/kg soil.

LAS SPIKED TO SLUDGE TEST:
- There was no significant difference in reproduction when control sludge was added to the control soil.
- LAS spiked to sludge at 300 mg a.i./kg soil (equivalent to 181 g a.i./kg sludge) did not affect the survival of adults or the reproduction (fertility: number of juvenile offspring)


COMPARISON OF SOIL AND SLUDGE SPIKED TESTS:

Compared to LAS directly spiked to soil, the reproductive output of organisms exposed to spiked sludge was not significantly different.
Reported statistics and error estimates:
- Linear, quadratic or logistic models were fitted to dose–response data by employing PROC NLMIXED (SAS Institute Inc, 2004) depending on the shape of the curve.
- The EC10 and LC10 values were estimated from initial, nominal concentrations and 95% confidence intervals for the predicted response (significance inferred at a = 5%). Survival was modelled assuming binomially distributed data and reproduction was modelled assuming normally distributed data.
- Determination of NOEC and treatment comparisons were made by ANOVA
- Means comparisons of the soil test, including only the control and the maximum LAS concentration, and the sludge test with and without LAS, were compared in a two-way ANOVA with interactions.
- The LAS and substrate effects were analyzed as main factors and simple effects within the soil substrate main effects by making contrasts.
Validity criteria fulfilled:
yes
Remarks:
(ISO 11267)
Conclusions:
In a long term toxicity tests with spiked soil, the 28 day EC10 value of sodium salt of linear alkyl benzene sulphonates (C10-C13) for Folsomia candida, based on reproduction, was 205 mg a.i./kg soil and the 28 day LC10 value, based on mortality, was 261 mg a.i./kg soil. Addition of non-spiked sludge or LAS spiked sludge to soil have no impact on the survival of adults or the reproduction (fertility: number of juvenile offspring).
Executive summary:

The toxicity potential of sodium salt of linear alkyl benzene sulphonates (C10-C13) was assessed for Folsomia candida in a sandy loam soil according to ISO 11267

Groups of F.candida were exposed to concentrations of 25-300mg LAS/kg soil for 28days.The adult survival and reproductive parameters were examined at the end of study.Test concentrations were analytically verified. In addition to LAS directly spiked to soil, test with LAS spiked to sludge (300 mg a.i./kg soil, corresponding to 0 and 181 g a.i./kg freeze-dried sludge) was also performed to study if this would change the toxicity compared with the soil test.

Survival of adult Folsomia candida was affected only slightly by LAS at the highest test concentration. There was no significant difference in survival and reproduction when control or LAS spiked sludge was added to the soil.

In a long term toxicity tests with spiked soil, the 28 day EC10 value of sodium salt of linear alkyl benzene sulphonates (C10-C13) for Folsomia candida, based on reproduction,was 205 mg a.i./kg soil and the 28 day LC10 value, based on mortality, was 261 mg a.i./kg soil. Addition of non-spiked sludge or LAS spiked sludge to soil have no impact on the survival of adults or the reproduction (fertility: number of juvenile offspring).

This long term toxicity study to Folsomia candida is classified as acceptable, and satisfies the guideline requirements for ISO 11267.

Endpoint:
toxicity to terrestrial arthropods: long-term
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Principles of method if other than guideline:
No standard guideline was followed. The test was performed according to a procedure described by Wiles and Krogh (1998) in tests with the collembolans Isotoma viridis, Folsomia candida and Folsomia fimetaria publication. The aim of study was to evaluate the toxicity potential of sodium salt of linear alkylbenzene sulfonate (C10-13) on the reproduction of Folsomia fimetaria. Test species were exposed to sodium LAS at five concentrations for 21 days. Four replicates were used per concentration. Ten male and 10 female collembolans were added to each replicate. At the end of the test period, the organisms were extracted using a controlled-temperature gradient extractor and animals were collected in cool collecting vessels with a bottom layer of plaster of Paris/charcoal.
GLP compliance:
no
Application method:
soil
Analytical monitoring:
no
Vehicle:
no
Details on preparation and application of test substrate:
LAS was dissolved in water, and added to soil so that water content equaled 50% of the water-holding capacity.
Test organisms (species):
Folsomia sp.
Animal group:
Collembola (soil-dwelling springtail)
Details on test organisms:
TEST ORGANISM
- Source: Danish National Environmental Research Institute
- Age at test initiation (mean and range, SD): adults
- Weight at test initiation (mean and range, SD): 10-30 ug, 0.8-1.4 mm long
Study type:
laboratory study
Limit test:
no
Total exposure duration:
21 d
Test temperature:
20 ± 1°C
pH (if soil or dung study):
6.2
Photoperiod and lighting:
400-800 lux for 12/12 hours photoperiod
Details on test conditions:
TEST SYSTEM
- Test container (material, size): 5.5 cm high x 6 cm diamter plastic cylinders with 1 mm mesh at bottom
- No. of organisms per container (treatment): 10 male/10 female
- No. of replicates per treatment group: 4
- No. of replicates per control: 4

SOURCE AND PROPERTIES OF SUBSTRATE (if soil)
- Geographic location: Askov (Danish soil)
- Soil texture (if natural soil)
- % sand: 62 (38.4% coarse sand and 23.6%, fine sand)
- % silt: 22.3 (10% coarse silt and 12.3%, fine silt)
- % clay: 13.0
- Soil classification system: sandy loam
- Organic carbon (%): 1.6
- CEC: 8.14 meq/100 g soil
- % Humus: 2.8
- pH: 6.2
- Pretreatment of soil: The soil samples were dried at 80 degrees C for 24 hours and sieved through a 2-mm mesh

OTHER TEST CONDITIONS
- Photoperiod: 12/12 hours
- Light intensity: 400-800 lux

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : number of organisms


Nominal and measured concentrations:
control, 50, 100, 200, 400, and 800 mg/kg soil dry weight
Reference substance (positive control):
no
Key result
Duration:
21 d
Dose descriptor:
EC10
Effect conc.:
161 mg/kg soil dw
Nominal / measured:
nominal
Basis for effect:
reproduction
Remarks on result:
other: 95% CL: 113-209 mg/kg soil dw
Key result
Duration:
21 d
Dose descriptor:
EC50
Effect conc.:
803 mg/kg soil dw
Nominal / measured:
nominal
Basis for effect:
reproduction
Remarks on result:
other: 95% CL: 560-1000 mg//kg soil dw
Key result
Duration:
21 d
Dose descriptor:
NOEC
Effect conc.:
200 mg/kg soil dw
Nominal / measured:
nominal
Basis for effect:
reproduction
Details on results:
50% mortality was not seen even at the highest concentration tested (800 mg/kg soil dw) and the LC50 could therefore not be estimated.
Reported statistics and error estimates:
Estimations of the 50 and 10% effect concentrations for reproductive output were done by logistic regression in SAS/INSIGHT Release 6.12. Data were fitted according to the following formulas, which showed a good fit to the dose response curves. For the EC50: juv= k (1+conc/EC50)c)-1; for EC10: juv= k (1+ (1/9)*(conc/EC10)c)-1. NOEC was assessed using ANOVA and Dunnett's procedure (at a 5% significance level) on the data. The 50% effect concentrations for lethality (LC50 values) were estimated by probit analysis in SAS/INSIGHT Release 6.12 (SAS, 1999).
Validity criteria fulfilled:
not specified
Remarks:
(No guideline was followed)
Conclusions:
In the reproduction test with Folsomia fimetaria, the 21 day EC10, EC50 and NOEC values of sodium salt of linear alkylbenzene sulfonate (C10-13) were 161 (95% CL: 113 -209) and 803 (95% CL: 560 -1000) and 200 mg/kg soil dw, respectively, based on reproduction.
Executive summary:

A study was conducted to evaluate the toxicity potential of sodium salt of linear alkylbenzene sulfonate (C10-13) on the reproduction of Folsomia fimetaria.

Test species were exposed to sodium LAS at nominal concentrations of 0, 50, 100, 200, 400, and 800 mg/kg soil dw of LAS for 21 days. Four replicates were used per concentration. Ten male and 10 female collembolans were added to each replicate. At the end of the test period, the organisms were extracted using a controlled-temperature gradient extractor and were collected in cool collecting vessels with a bottom layer of plaster of Paris/charcoal. Thereafter, the number of organisms were counted.

Fifty prcent mortality was not seen even at the highest concentration tested (800 mg/kg soil dw) and the LC50 could therefore not be estimated. The LC50 value was >800 mg kg dry weight.

In the reproduction test with Folsomia fimetaria, the 21 day EC10, EC50 and NOEC values of sodium salt of linear alkylbenzene sulfonate (C10-13) were 161 (95% CL: 113 -209) and 803 (95% CL: 560 -1000) and 200 mg/kg soil dw, respectively, based on reproduction.

Endpoint:
toxicity to terrestrial arthropods: long-term
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 232 (Collembolan Reproduction Test in Soil)
Deviations:
yes
Remarks:
Replicates of control and number of test concentrations were not used as recommened by Guideline
GLP compliance:
no
Application method:
soil
Analytical monitoring:
yes
Details on sampling:
Samples of two concentration levels were taken 2, 17, and 31 days after the soil was spiked with LAS.
Details on preparation and application of test substrate:
LAS was dissolved in water and mixed with 30 g moist soil (25.5 g dry). The mixture was prepared immediately before the experiment.
Test organisms (species):
Folsomia sp.
Animal group:
Collembola (soil-dwelling springtail)
Details on test organisms:
- Source: A laboratory culture was established from field-collected animals that were mass reared on a moistened substrate of plaster of Paris/charcoal.
- Age at test initiation: 23-26 days adults for reproduction study, 0 to 3 days juveniles for growth study and 0 to 1 day juveniles for molting frequency study.
Study type:
laboratory study
Limit test:
no
Remarks:
Total exposure duration was 20-21 days
Test temperature:
20°C
pH (if soil or dung study):
5.5
Photoperiod and lighting:
12 hrs light/12 hrs dark
Details on test conditions:
- Amount of soil or substrate: 30 g moist soil for growth and reproduction studies and compressed surface of soil in multidishes (Nunclony, NUNC) with 24 circular holes for molting study
- No. of organisms per container (treatment): 10 male/10 female per replicate for growth and reproduction studies and 22 to 28 juveniles per concentration for molting study
- No. of replicates per treatment group: 4 for growth and reproduction studies and 1 for molting study
- No. of replicates per control: 4 for growth and reproduction studies and 1 for molting study

SOURCE AND PROPERTIES OF SUBSTRATE (if soil)
- Geographic location: Speyer, Germany
- Soil texture (if natural soil)
- % sand: 34.8
- % silt: 5.6
- % clay: 5.2
- % gravel: 54.6
- Organic carbon (%): 2.3
- Pretreatment of soil: The soil was dried at 80 degrees C
- Storage (condition, duration): The soil was stored at 5 degrees C until use.

OTHER TEST CONDITIONS
- Photoperiod: 12/12 hours

EFFECT PARAMETERS MEASURED (with observation intervals if applicable):

1. The survival and reproduction was determined for adults after 21 days of exposure using digital image processing.
2. The juveniles were counted after 21 days of exposure and their individual lengths were measured by use of digital image processing
2. Molting frequency of juveniles: The multi-dishes with test organisms were assessed every second day.
Nominal and measured concentrations:
Nominal concentrations for growth and reproduction studies: 0-1000 mg/kg dry soil (0, 200, 300, 500, 700 and 1000 mg/kg based on the graphs available in the study)

Nominal concentrations for molting frequency study: 0, 300, and 600 mg/kg dry soil
Key result
Duration:
21 d
Dose descriptor:
EC10
Effect conc.:
147 mg/kg soil dw
Nominal / measured:
nominal
Basis for effect:
reproduction
Remarks on result:
other: 95% CL: 116-178 mg/kg soil dw
Key result
Duration:
21 d
Dose descriptor:
EC10
Effect conc.:
163 mg/kg soil dw
Nominal / measured:
nominal
Basis for effect:
growth
Remarks on result:
other: 95% CL: 132–194 mg/kg soil dw
Key result
Duration:
20 d
Dose descriptor:
EC10
Effect conc.:
185 mg/kg soil dw
Nominal / measured:
nominal
Basis for effect:
other: Molting frequency
Remarks on result:
other: 95% CL: 142–227 mg/kg soil dw
Key result
Duration:
21 d
Dose descriptor:
EC10
Effect conc.:
196 mg/kg soil dw
Nominal / measured:
nominal
Basis for effect:
mortality
Remarks on result:
other: 95% CL: 99–278 mg/kg soil dw
Details on results:
Survival and reproduction of adults
- Adult survival was unaffected at all concentrations.
- Reproductive output decreased linearly with increasing concentration, with 430 juveniles produced in control containers, to only 150 juveniles produced at the highest concentration (1000 mg/kg dw soil).

Survival and growth of juveniles
- With increasing concentrations of LAS, juvenile survival declined to about 20% at 700 mg/kg and above.
- Length increase of control animals was approximately 0.6 mm compared to a length increase of approximately 0.3 mm of animals exposed to 700 mg/kg.

Molting frequency of juveniles
- Control juveniles molted on the average 4.3 times during 20 days, whereas molting at 300 and 600 mg/kg was reduced to 3.7 and 2.9 times, respectively.
Reported statistics and error estimates:
Data were analyzed for normality by means of the x2 test for normality, and for homogeneity of variance by Bartlett’s test. Estimation of the NOEC and LOEC was done with ANOVA by use of Dunnett’s test. Effective concentration (x%) (ECx) values and the corresponding confidence interval were estimated by means of regression procedures using the SAS procedure PROC NLIN. Lethal concentration (x%) (LCx) values for juveniles were estimated by use of PROBIT analysis.

Table 1: Effect of linear alkylbenzene sulfonate on reproductive output, survival of juveniles, juvenile growth, and juvenile molting frequency of Folsomia fimetaria. Effect concentrations (based on initial nominal concentrations) with 95% confidence interval (mg/kg dry soil) (Holmstrup and Krogh, 1996)

Parameter EC10 value EC50 value NOEC LOEC
Reproductive output 147 (116–178) 737 (538–890) 500 1000
Growtha 163 (132–194) 896 (777–1,015) <200 200
Molting frequency 185 (142–227) 923 (708–1,137) <300 300
Survival 196 (99–278) 570 (454–689) 500 700

a: Length increase during 21 days

Validity criteria:

1.       Survival of adult and newly hatched juveniles in control treatments was about 90%.

2.       No of juveniles per each test container in control was 430.

3.       No information on no of juveniles per replicate was provided.

Validity criteria fulfilled:
yes
Remarks:
(OECD Guideline 232 principles were fulfilled i.e survival was about 90% and there were 432 number of juveniles in controls containers)
Conclusions:
In a long term toxicity study with Folsomia fimetaria, the 21 day EC10 values of LAS (average carbon chain length 11.53) were 147 mg/kg dw soil (reproduction), 163 mg/kg dw soil (growth) and 196 mg/kg dw soil (survival). The 20 day EC10 value, based on molting was 185 mg/kg dw soil.
Executive summary:

A toxicity study was conducted to evaluate the direct effects of LAS (average carbon chain length 11.53) on mortality, growth, molting rate, and reproduction of Folsomia fimetaria in the laboratory.

Two tests with either newly hatched individuals or adults (16–19 days old) were conducted. In both the studies, groups of 10 male and 10 females (per replicate; 4 replicates) of F. fimetaria were exposed to concentrations of LAS ranging from 0-1000 mg/kg dw soil for 21 days. This was followed by extraction in a high-gradient extracting system. An additional study was conducted to evaluate the effect of LAS on the molting frequency of Folsomia fimetaria. Juveniles 0 to 1 day of age (22 to 28 juveniles per concentration) were exposed to 0, 300, and 600 mg/kg dry soil LAS for a period of 20 days. The molting rate was determined throughout the exposure period.

The survival and reproduction was determined for adults and the juveniles were counted after 21 days. The individual lengths of juveniles were also measured at the end of exposure. Molting frequency of juveniles was analyzed in multi-dishes with test organisms were assessed every second day

There was no effect on adult survival, however, there was a dose-related decrease in reproduction. With increasing concentrations of LAS, juvenile survival also declined in 700 mg/kg and above concentrations. Length increase of control animals was approximately 0.6 mm compared to a length increase of approximately 0.3 mm of animals exposed to 700 mg/kg. Control juveniles molted on the average 4.3 times during 20 days, whereas molting at 300 and 600 mg/kg was reduced to 3.7 and 2.9 times, respectively.

In a long term toxicity study with Folsomia fimetaria, the 21 day EC10 values of LAS (average carbon chain length 11.53) were 147 mg/kg dw soil (reproduction), 163 mg/kg dw soil (growth) and 196 mg/kg dw soil (survival). The 20 day EC10 value, based on molting was 185 mg/kg dw soil.

Endpoint:
toxicity to terrestrial arthropods: long-term
Remarks:
(multiple short and long term studies)
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Reason / purpose for cross-reference:
reference to same study
Qualifier:
no guideline followed
Principles of method if other than guideline:
not specified
GLP compliance:
not specified
Application method:
not specified
Analytical monitoring:
not specified
Vehicle:
not specified
Test organisms (species):
other: Folsomia fimetaria, Folsomia candida, Hypoaspis aculeifer, Isotoma viridis, Hypogastrura assimilis, Platynothrus peltifer
Animal group:
other: soil-dwelling
Details on test organisms:
eleven soil dwelling invertebrate species
Study type:
other: no data
Reference substance (positive control):
not specified
Key result
Dose descriptor:
EC10
Effect conc.:
41 mg/kg soil dw
Basis for effect:
growth
Remarks on result:
other: Isotoma viridus
Key result
Dose descriptor:
NOEC
Effect conc.:
320 mg/kg soil dw
Basis for effect:
reproduction
Remarks on result:
other: Platynothrus peltifer
Key result
Dose descriptor:
EC10
Effect conc.:
96 mg/kg soil dw
Basis for effect:
reproduction
Remarks on result:
other: Folsomia fimetaria
Key result
Dose descriptor:
EC10
Effect conc.:
18 mg/kg soil dw
Basis for effect:
reproduction
Remarks on result:
other: Folsomia candida
Key result
Dose descriptor:
EC10
Effect conc.:
81.7 mg/kg soil dw
Basis for effect:
reproduction
Remarks on result:
other: Hypoaspis aculeifer
Key result
Dose descriptor:
EC10
Effect conc.:
99.8 mg/kg soil dw
Basis for effect:
reproduction
Remarks on result:
other: Hypogastrura assimilis
Details on results:
Values were extracted from a variety of original references and compiled for this article.

Table 1: The following table shows the available NOEC, EC10 and EC50values for eleven soil dwelling invertebrate species (in mg/kg dry weight) (Jensen et al., 2001).

                                  

Species

Endpoint

NOEC

EC10

EC50

Eisenia foetida

Reproduction

383

558

Lumbricus terrestris

Weight

667

Aporrectodea caliginosa

Reproduction

14

129

Aporrectodea longa

Reproduction

27

137

Folsomia fimetaria

Reproduction

96

442

Folsomia candida

Reproduction

18

91

Hypoaspis aculeifer

Reproduction

81.7

236

Enchytraeus albidus

Reproduction

6.2

40.5

Platynothrus peltifer

Reproduction

320

467

Isotoma viridis

Growth

41

Hypogastrura assimilis

Reproduction

99.8

421

Validity criteria fulfilled:
not specified
Remarks:
(No guideline was followed)
Conclusions:
The EC10 values of LAS for Folsomia fimetaria, Folsomia candida, Hypoaspis aculeifer, Isotoma viridis and Hypogastrura assimilis were 96, 18, 81.7, 41 and 99.8 mg/kg dry weight. The NOEC for Platynothrus peltifer was 320 mg/kg dry weight.
Executive summary:

Various studies on terrestrial toxicity of LAS were performed with terrestrial organisms. The EC10 values of LAS for Folsomia fimetaria, Folsomia candida, Hypoaspis aculeifer, Isotoma viridis and Hypogastrura assimilis were 96, 18, 81.7, 41 and 99.8 mg/kg dry weight. The NOEC for Platynothrus peltifer was 320 mg/kg dry weight.

Description of key information

A series of studies conducted with LAS on terrestrial arthropods are summarized below.

Study 1 (C10-13 LAS):

Various studies on the terrestrial toxicity of C10-13 LAS, sodium salt were performed with terrestrial organisms. The EC10 values for Folsomia fimetaria, Folsomia candida, Hypoaspis aculeifer, Isotoma viridis and Hypogastrura assimilis were 96, 18, 81.7, 41 and 99.8 mg/kg soil dry weight (dw). The NOEC for Platynothrus peltifer was 320 mg/kg soil dry weight (dw) (Jensen, 2001).

Study 2 (C10-13 LAS):

Groups of 10 male and 10 female Folsomia fimetaria were exposed to various concentrations of C10 -13 LAS, sodium salt in three different soil types for 21 d. At the end of this period, the number of adult and juvenile organisms was counted. Another test was done to compare the toxicity of three LAS salts (Na, Ca and Mg) in one soil type (sandy). There was little variation in toxicity among the three soil types and in the three salt species. The EC10 for Folsomia fimetaria in various soils ranged from 85-93 mg/kg soil dw.

Study 3 (C10-13 LAS):

The toxicity of C10-13 LAS, sodium salt, was assessed in Folsomia candida using a sandy loam soil according to ISO Method 11267. Groups of F. candida were exposed to concentrations of 25-300 mg /kg soil dw for 28 d. Adult survival and reproductive parameters were examined at the end of study. Test concentrations were analytically verified. In addition to LAS directly spiked to soil, test with LAS spiked to sludge (300 mg a.i./kg soil dw, corresponding to 0 and 181 g a.i./kg freeze-dried sludge) was also performed to study if this would change the toxicity compared with the soil test. Survival of adult Folsomia candida was affected only slightly by the test substance at the highest test concentration. There was no significant difference in survival and reproduction when control or LAS-spiked sludge was added to the soil. In a long term toxicity tests with spiked soil, the 28 d EC10 for Folsomia candida, based on reproduction, was 205 mg a.i./kg soil dw and the 28 d LC10, based on mortality, was 261 mg a.i./kg soil dw. Addition of non-spiked sludge or LAS spiked sludge to soil have no impact on the survival of adults or the reproduction (fertility: number of juvenile offspring) (Krogh, 2007).

Study 4 (C10-13 LAS):

A study was conducted to evaluate the toxicity potential of C10-13 LAS, sodium salt, on the reproduction of Folsomia fimetaria. Test species were exposed at nominal concentrations of 0, 50, 100, 200, 400 and 800 mg/kg soil dw of LAS for 21 days. Four replicates were used per concentration. Ten male and 10 female collembolans were added to each replicate. At the end of the test period, the organisms were extracted using a controlled-temperature gradient extractor and were collected in cool collecting vessels with a bottom layer of plaster of Paris/charcoal. Thereafter, the number of organisms were counted. Fifty percent mortality was not seen even at the highest concentration tested (800 mg/kg soil dw) and the LC50 could therefore not be estimated. The LC50 value was >800 mg kg soil dw. In the reproduction test with Folsomia fimetaria, the 21 d EC10, EC50 and NOEC values were 161 (95% CL: 113 -209) and 803 (95% CL: 560 -1000) and 200 mg/kg soil dw, respectively, based on reproduction (Jensen, 2002).

Study 5 (C10-13 LAS):

The effects of C10-13 LAS, sodium salt (average alkyl chain length C11.6) were evaluated on the reproduction of springtails and predacious mites. Ten males and ten females of two springtails species (Folsomia fimetaria and Hypogastrura assimilis) were exposed to the test substance through soil after 24 h equilibration of the soil. In another test, ten female and five male Hypoaspis aculeifer were added to each container together with 100 Folsomia fimetaria serving as prey for the mites. The containers were incubated for 21 d. After incubation, the animals were extracted using MacFadyen high-gradient extraction and the number of offspring were counted. Reproduction in the Folsomia fimetaria, Hypogastrura assimilis and Hypoaspis aculeifer was reduced by 50% at approximately 424, 421 and 236 mg/kg soil dw, respectively. Survival of Folsomia fimetaria and Hypoaspis aculeifer was not affected, even at the highest concentration of 793 mg/kg soil dw, whereas the effects on survival for Hypogastrura assimilis were not assessed because the earliest produced juveniles rapidly matured and were not discernible from the added adults. In three reproduction tests with soil invertebrates, the EC10 values were 85, 99 and 82 mg/kg soil dw for Folsomia fimetaria, Hypogastrura assimilis and Hypoaspis aculeifer, respectively. Survival of Folsomia fimetaria and Hypoaspis aculeifer was not affected, even at the highest concentration of 793 mg/kg soil dw (Holmstrup, 2001; Krogh, 1998).

Study 6 (10-13 LAS):

A toxicity study was conducted to evaluate the effects of LAS, sodium salt (average carbon chain length 11.53) on mortality, growth, molting rate and reproduction of Folsomia fimetaria in the laboratory. Two tests with either newly hatched individuals or adults (16–19 days old) were conducted. In both the studies, groups of 10 male and 10 females (per replicate; 4 replicates) of F. fimetaria were exposed to concentrations of LAS ranging from 0-1000 mg/kg dw soil for 21 days. This was followed by extraction in a high-gradient extracting system. An additional study was conducted to evaluate the effect of LAS on the molting frequency of Folsomia fimetaria. Juveniles 0 to 1 day of age (22 to 28 juveniles per concentration) were exposed to 0, 300, and 600 mg/kg dry soil LAS for a period of 20 days. The molting rate was determined throughout the exposure period. The survival and reproduction was determined for adults and the juveniles were counted after 21 days. The individual lengths of juveniles were also measured at the end of exposure. Molting frequency of juveniles was analyzed in multi-dishes with test organisms were assessed every second day. There was no effect on adult survival, however, there was a dose-related decrease in reproduction. With increasing concentrations of LAS, juvenile survival also declined in 700 mg/kg and above concentrations. Length increase of control animals was approximately 0.6 mm compared to a length increase of approximately 0.3 mm of animals exposed to 700 mg/kg. Control juveniles molted on the average 4.3 times during 20 days, whereas molting at 300 and 600 mg/kg was reduced to 3.7 and 2.9 times, respectively. In a long term toxicity study with Folsomia fimetaria, the 21 day EC10 values of LAS (average carbon chain length 11.53) were 147 mg/kg dw soil (reproduction), 163 mg/kg dw soil (growth) and 196 mg/kg dw soil (survival). The 20 day EC10 value, based on molting, was 185 mg/kg dw soil (Holmstrup, 1996).

Key value for chemical safety assessment

Additional information